Intervention or workovers on subsea equipment failures can be very expensive and time-consuming. If problems can be diagnosed and/or predicted before the system fails, a lot of operational expenditures could be saved from projects by planning interventions prior to system failures.
A hydraulic control system of subsea equipment is a key component whose integrity greatly impacts the functionality of a subsea production system. The failure of hydraulic control systems should be prevented or fixed as soon as possible by all means to ensure normal operation of the subsea production system. Some of the common failure modes associated with hydraulic control systems include, for example, supply/function tube or directional control valve (DCV) leaking, subsea filter clogging, accumulator pre-charge gas escaping, and actuator spring force and seal friction changing.
A conventional method of predicting subsea hydraulic failures relies on an operator who visually reviews valve signatures and tells about the system problems. The effectiveness of such manual diagnosis dependents largely on the experience of the operator; and even a skilled operator cannot always detect small changes in the valve signatures that occur over time or determine whether such changes are due to failing components or normal operation condition changes such as bore pressure and hence the associated spring force.
There exists a need for a hydraulic diagnostic tool. Such a tool should be designed to detect and diagnose failure modes of subsea hydraulic control system prior to failure to reduce intervention costs and production downtime. There also exists a need for a method for monitoring a communication system of a subsea system prior to failure to reduce intervention costs and production downtime.